void ExposureTargetOffsetChanged (NSObservedChange obj)
{
var newValue = obj.NewValue;
if (newValue != null && newValue != NSNull.Null) {
float newExposureTargetOffset = newValue.AsFloat ();
DispatchQueue.MainQueue.DispatchAsync (() => {
ExposureTargetOffsetSlider.Value = newExposureTargetOffset;
ExposureTargetOffsetValueLabel.Text = newExposureTargetOffset.ToString ("F1", CultureInfo.InvariantCulture);
});
}
}